Thermal timing device



May 23, 1950 P. J. M CULLOUGH THERMAL TIMING DEVICE 2 Sheets-Sheet 1Filed Nov. 21, 1945 Y L E TL N N U R EC w Vc WM M J- L U A P 4 Y 2 a a 3C 2 In n M F mh v u; l I 7 v 5 0 X 5 IN mfd W5 2 9 Z 7 May 23, 1950 P.J. MCCULLOUGH THERMAL TIMING DEVICE heats-Sheet 2 FIG .8.

FiG .7.

INVENTOR'.

PAULJ.MC CULLOUGH BY @447 M ATTORNEY Patented M za- 1950 THERMAL TIMINGDEVICE Paul J. McCullough, St. Louis, Mo., assignor, by

memo assignments, to The Toastswell Company, Incorporated, St. Louis,Mo., a corporation of Missouri Application November 21, 1945, Serial No.629,947

4 Claims. (Cl. 200-122) The invention relates to devices for controllingelectrically operated apparatus, such as electric toasters or othercookers, and more particularly to such apparatus which is set for aheating operation during a single period and then acts automatically toterminate the heating operation.

One object of the invention is to simplify the mechanismfor.automatically timing the period of operation of electricalapparatus.

thereon. Slice supports ll, rigid with carriage l0, extend into thetoasting compartments 1 1 a parts mounted thereon in the elevatedposition Another object is to provide, in electric toasters or othercookers, substantially uniform cooking of the product irrespective ofwhether the device is hot or cold at the start of the period.

These and other detail objects of the invention as will appear below areattained by the structure shown in the accompanying drawings, whichstructure is intended to be illustrative and not exclusive of otherarrangements embodying the general inventive principles. In thesedrawings:

Figure 1 is a side view of a toaster with a portion of the housing cutaway and showing the interior construction.

Figure 2 is a transverse vertical section taken approximately on theline 2-2 of Figure 1.

Figure 3 is a detail vertical section on line 3-3 of Figure 2 and showsthe snap for holding the carriage in lowered toasting position and there= lease therefor.

Figure 4 is a similar section showing the position of the thermostatcontrol and release after resetting the toaster for an operationfollowing a previous operation and before the thermostat coolssufliciently to return to its original position.

Figure 5 is a horizontal section taken approxi= mately on line 5-5 ofFigure l and shows the thermostat control when cold.

Figure 6 is a section similar to Figure 5 showing the thermostat controlwhen heated to a predetermined temperature.

Figures 7 and 8 are detail views of the switch in the positions shown inFigures 6 and 5, respectively. 1

Figure 9 is a schematic wiring diagram.

The toaster comprises a housing 9, a base and end plates 3 and 4 securedat the top by channels 5 and at the bottom being bent substantially atright angles to form flanges 8 and 9 attached to base 2. End plates 3and 4 are spaced from each other longitudinally of the toaster andsupport spaced parallel heating units 6 positioned perpendicular theretoto form toasting chambers l. .v

A carriage I0 having lugs H slidably supported in slots l2 in end plate4 moves up and down indicated in dotted lines in Figures 1 and 2;

'A bracket i1, rigid with carriage It, extends through a slot l8inhousing I and mounts a handle is vby which carriage I 0 and associatedparts may be moved manually from the elevated non-toasting positionshown in dotted lines in Figures 1 and 2 to the lowered toastingposition shown in solid lines in Figures 1 and 2. In this loweredposition a spring snap 20 (Figures 3 and 4) attached to carriage IE andextending below the bottom edge thereof enters a slot 2i in the bottomof end plate 4 at flange 9 and engages a boundary of the slot to holdcarriage ID in lowered position against upward movement by spring 94.Further downward movement of carriage ii is prevented by an extension 22at the bottom thereof engaging flange 9 (Figure 2).

The toaster is connected to a current supply line by a two wire cord 23having the usual fitting 23a at its outer end for plugging into asuitable outlet. One of the cord wires is secured to a binding post 24connected by a wire 25 at terminal 26 to a lead 21a attached to one endof a resistance heating uniti2l closely associated with and arranged toheat a thermo-bar 34, described more fully below. Ifhe other end ofresistance unit 2! is attached to a lead 21b connected at terminal 35 toa wire 30 leading to bus bar 32 to which is connected one end of each ofthe heating units 6, the other end of each heating unit being connectedto a bus bar 33 thus providing a parallel circuit for the heating unitsbetween bus bars 32 and 33. Bus bar 33 is connected to a contact 35adjacent to but spaced from a contact 36 to which the second wire ofcord 23 is attached.

Contacts 35 and 36 are connected and disconnected electrically by adisc-like member 31 carried by an arm 38 extending transversely of thetoaster from one end of a shaft 39 journalled in a slot 40 in end plate3 and in a notch 4! in end plate 4. A tab 42 overlies notch 4| and holdsthe shaft therein. At the other end of shaft 3! is an arm 43 extendingtransversely of the toaster through a slot 44 in a bracket 45 attachedto carriage Ill and movable thereby. Member 31 moves toward and awayfrom contacts 35 and 38 as carriage i4 is lowered and raised andpreferably engages contacts 35 and 33 shortly before carriage ll reachesits lower limit. Arms 38 and 43 and shaft 39 are formed of spring wireand are distorted slightly during additional movement of carriage II). Aswitch comprising contacts 35 and 33 and member 31, as described above,is disclosed in a copending application, Serial No. 471,686, fliedJanuary 8, 1943, which has resulted in Patent No, 2,503,959, dated April11, 1950.

Thermo-bar 34, positioned adjacent heater 31, when cold is flexed towardthe heater, as shown in Figure 5, between a grooved bracket 43 attachedrigidly to flange 9 of end plate 4 and a grooved lug 41 supportedyieldingly by a flat spring 48 attached 'at one end to a bracket 49fastened rigidly to flange 9 or end plate 4. The ends of a coiledtension spring 50 are attached to bracket 46 and to flat spring 48 tomaintain thermo-bar 34 flexed even after initial heating untilthermo-bar 34 reaches a predetermined temperature suiflcient to cause itto flex suddenly away from heater 21 against tension of spring 54 to thepositionshown in Figure 6. Flexure of thermo-bar 34 toward and away fromheater 31 is limited by a member cut out at 52 to receive thermo-bar 34.Member Si is attached to the bottom of flange 9 of end plate 4 (Figures1, 3 and 4).

A lever 60 is slotted vertically at 5|, near the top, and is slidablysupported on bracket l1 by a rivet 62 in slot iii. The lever has at itslower end a finger 63 engaging snap 20. With carriage III in toastingposition as shown in solid lines in Figures 1 and 2, the lower end oflever 60 lies adjacent thermo-bar 34 when the thermo-bar is flexedtoward heater 21 so that as thermo-bar 34 flexes away from heater 21 atthe end of a period, from the position shown in Figure 5 to the positionshown in Figure 6, it moves the lower end of lever 60 to the rightwhereby finger 63 trips snap 20 and releases carriage as shown in Figure3. Carriage it then is raised by spring I4 to the position shown indotted lines in Figures 1 and 2.

Attached to thermo-bar 34 near the center thereof by a hook 53 is a rod54 extending substantially the full length of the toaster. The rod 54 issupported near one end in a vertical slot 55 in member 5! attached toflange 9 (Figure 2) and near the other end in a diagonal slot 56 in endplate 3 (Figures '1 and 8). Rod 54 slides to and fro in slots 55 and 56as thermo-bar 34 flexes from one position to the other for the purposedescribed below.

Resistance heating unit 21 is supported pivotally at one end by a hook28 attached to the lower side of flange 9 by a screw 29. To shorten orlengthen a timing period, the free end of heater 21 can be moved aboutits pivot on hook 28 toward or away from thermo-bar 34 by a screw 51threaded into base 2 and rotated by knob 58. With this arrangement,toast of any desired color can be made automatically. The free end ofheater 21 is urged yieldingly against screw 51 and away from thermo-bar34 by leads 21a and 21b which preferably are made of spring material andconnect the ends of heater element 21 to terminals 26 and 3|,respectively, as described above.

Flange 9 of end plate 4 is cut away at 59 adjacent thermo-bar 34 andheater 21 to permit circulation of air about thermo-bar 34 to cool it asrapidly as possible at the nd of a timing period.

4 The timing device operates as follows: To begin an initial toastingperiod when the toaster is cold, handle 13 is pushed downwardly from theupper non-toasting position shown in dotted lines in Figure 1 to thelowered toasting position shown in solid lines in Figure 1 wherebyspring snap 28 on carriage Ill engages flange 3 at slot 2| to holdcarriage l0 and associated parts inthis position against the pull ofspring l4. As carriage I8 is lowered, member 31 completes the circuitthrough contacts 35 and 33 whereupon heating ]units 6 and heater 21,associated with thermo-bar 34, are energized to begin a toasting period.The period continues until thermo-bar 34 is heated to a predeterminedtemperature suflicient to cause it to snap against tension of spring 58from the position shown in Figure 5 to the position shown in Figure 8 tomove lever 60 to the right (Figure 3) causing flnger 63 to release snap20, as described above, whereby carriage l0 and associated parts moveupwardly to non-toasting position and open contacts 35 and 36 to end thetoasting period.

To begin an immediate subsequent period, carriage III is pusheddownwardly, as described above. However, if thermo-bar 34 has not cooledsufliciently to permit it snap back to the position shown in Figure 5,lever 30 moves downwardly with carriage l0 until its bottom edge restson the top of thermo-bar 34 (Figure 4). During further downward,movement of carriage l8, lever v6i] slides on rivet 62 in lever [1.Also, rod 54, moved to the right by thermo-bar 34 during its snap actionat the termination of the previous period, engages arm 38 andtemporarily prevents member 31 from closing contacts 35 and 38 (Figures6 and '7) until thermo-bar 34 cools sufficiently to snap back to theposition of Figure 5 whereby rod 54 is moved to the left and disengagesarm 38 permitting member 31 to close contacts 35 and 35 to begin thetoasting period (Figures 5 and 8). Simultaneously, lever 88 dropsdownwardly between thermo-bar 34 and snap 20 in position to trip snap 20at the termination of the period when the thermo-bar 34 is heatedsufllciently to snap again to the position of Figures 3 and 6. Theremainder of the cycle is then repeated.

Thermo-bar 34, in an immediate subsequent period, does not cool to atemperature as low as at the beginning of an initial period, when thetoaster is cold, hence an initial period is longer than an immediatesubsequent period.

As explained above, light or dark toast may be had at will by turningknob 58 which pivots heater 2! toward or away from thermo-bar 34 toshorten or lengthen the toasting period.

In some instances it may be desirable to inspect the toast before thetoasting period is termlnated automatically by the timing device. Thisis done by pushing handle l9 upwardly sufl'iciently to overcome frictionof snap 30, whereupon carriage i0 is moved upwardly to non-toastingposition by spring 14.

A timing device of the kind described is simple in construction andoperation, yet provides for variations in the length of the initialperiod, when the toaster is cold, as compared to periods immediatelyfollowing when the toaster is hot at the start, so that the finishedtoast is substantially uniform for any setting of knob 58.

The details of the construction may be varied substantially withoutdeparting from the spirit of the invention and the exclusive use of suchmodifications as come within the scope of the claims is contemplated.While there is shown a timing device constructed according to theinvention adapted for use on an electric toaster, it should beunderstood that the timing device can be used on other electricalequipment also.

What is claimed is:

1. In a timing device for an electric circuit, a movable support, amanually operable handle for moving said support to initiate a timingperiod, a switch member mounted on said support and movable with saidsupport between circuit opening and circuit closing positions, areleasable element for holding said switch member in circuit closingposition upon the initiation of a timing period, a heater connected inthe circuit. a thermo-bar closely associated with said heater and heatedthereby when said switch member is in circuit closing position, atension spring across the ends of said thermo-bar flexing saidthermo-bar in one direction when the bar is cold, said thermo-bar whenheated to a predetel-mined temperature being arranged to flex in theopposite direction against the tension of said spring and suddenlyrelease said element, thereby opening the switch to terminate the timingperiod, a part connected to said thermo-bar,

said thermo-bar, when heated, projecting said part into the path of saidsupport to prevent said switch member from closing the circuit, and saidthermo-bar, when cooled, moving said part out of the path of saidsupport so that said switch member may close the circuit.

2. In an electrical timing device, a switch, a heater connectedelectrically to said switch, a pivot mounting one end of said heater, athermobar for controlling said switch and heated by said heater, aspring extending across the ends of the thermo-bar and flexing thethermo-bar, when cooled, towards said heater, said thermobar when heatedto a predetermined temperature flexing against the tension of 'saidspring away from said heater to open said switch, thereby terminating atiming period, an adjustable part for moving the other end of saidheater toward and away from said thermo-bar to vary the time necessaryto heat the thermo-bar to 6 the predetermined temperature and therebyvary the length of the timing period.

3. In a timing device for an electric circuit, a yielding support, aswitch member mounted on said support and movable with said supportbetween circuit opening and circuit closing positions, a releasableelement for holding said switch member in circuit closing position uponthe initiation of a timing period, a heater connected in said circuit, athermo-bar heated by said heater when said switch member is in circuitclosing position, a tension spring across the ends of said thermo-barflexing said thermo-bar, when cold, towards said heater, said thermo-barwhen heated to a predetermined temperature being arranged to flex awayfrom said heater against the tension of said spring and suddenly releasesaid element thereby opening the switch to terminate the timing period,a rod connected substantially to the center of the thermo-bar, saidthermo-bar when heated moving said rod to a position for engaging saidsupport to prevent said switch member from closing the circuit when saidsupport is moved toward circuit closing position, and said thermo-bar,when cold, disengaging said rod from said support so that said supportmay yield and urge said switch member into circuit closing position.

4. A device as described in claim 3 in which a pivot mounts one end ofthe heater, and an adjustable part moves the other end of the heatertoward and away from the thermo-bar to vary the time necessary to heatthe thermo-bar to vary the length of the timing period.

PAUL J. MCCULLOUGH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,254,687 Koci Sept. 2, 19412,302,117 Gomersall Nov. 17, 1942 2,363,169 Fischer Nov. 21,19442,426,620 Koci Sept. 2, 194!

